13 Benefits of the Marimo Moss Ball

Marie is a lover of everything about and inside of aquariums. Among other friendly creatures, she has a turtle that she adores.

Live plants are very beneficial for aquariums. They do everything from absorbing toxic nitrates to giving your animals a natural, beautiful environment to live in.

Unfortunately, not all of us have green thumbs. Over the years, I have struggled to keep live plants in my aquariums, even easy ones like Anacharis and jungle val, both of which have died on me.

So what’s one to do? Out of all the live plants I have had in my aquariums, there is one plant (well, sort of plant) that has not failed me: the Marimo moss ball.

Is It Really Moss?

The moss ball is not to be confused with cheap knockoffs (Java wrapped around plastic or foam spheres). Instead, Marimo moss balls are little squishy balls of algae that look a lot like moss, hence the name. In the wild, they roll along the bottoms of rivers, giving them their round shape. They are also viewed as charms in Japan and even treated as pets.

Marimo Moss Ball Basic Facts

Benefits of the Marimo

Aside from its unique appearance, here are some benefits of having a Marimo moss ball in your aquarium.

1. Sucks Up Nitrates and Other Nasties
2. Provides Some Oxygen
3. Helps Prevent Excess Algae Growth
4. Harbors a Good Amount of Beneficial Bacteria
5. Requires Almost Zero Maintenance
6. Easily Adapts to High pH
7. Is Beloved by Shrimp (and Other Creatures)
8. Is Snail-Proof
9. Does Not Produce Dead Matter
10. Tolerates Salt Well
11. Does Not Bring Hitchhikers With It Into the Tank
12. Doesn't Need to Be Anchored
13. Is Almost Impossible to Kill

1. Sucks Up Nitrates and Other Nasties

Byproducts of fish waste, nitrates are harmless to most healthy fish under 30 ppm, but as their numbers increase over time, they can stress and kill your fish. Partial water changes are performed to keep nitrates in check.

Like live plants, moss balls absorb nitrates. But—also like plants—it’s usually not a large amount. The ball would make a difference only if it were kept in just a few gallons of water. Still, any nitrate absorbent is a benefit to your tank’s ecosystem. Moss balls are also like little filters, sucking up debris and small amounts of ammonia and phosphates.

2. Provides Some Oxygen

Like plants in general, moss balls suck up CO₂ and release oxygen into the water. If you don’t like noisy air stones, some Marimo moss balls are a great addition to help you oxygenate your tank.

3. Helps Prevent Excess Algae Growth

What better way to combat algae than with algae? Marimo moss balls suck up the same nutrients as undesirable algae, depriving invasive algae of those nutrients. I had brown algae growing in my 10-gallon tank, but since wiping them off the glass and adding a few moss balls, they have yet to grow back. Of course, moss balls won’t make that much of an impact in larger aquariums unless you get a lot of them. I don’t know about killing off algae, but they can help prevent unwanted algae from growing back.

4. Harbors a Good Amount of Beneficial Bacteria

While gravel and filter media is the most valuable seeding items for a new tank, the Marimo moss ball, like many plants, has colonized beneficial bacteria on its surfaces, and can make for great seeding material. I wouldn’t put one in a filter (in fear of hurting the moss ball) but they can help with the nitrogen cycle.

5. Requires Almost Zero Maintenance

The moss ball requires freshwater, some amount of lighting (prefers shading in bright tanks), and waste to feed off of. So basically, as long as you have an aquarium set up with aquatic animals, you’ve already got everything the algae ball needs. Every time you feed your fish, you are also feeding the moss ball, so no fertilizers are required.

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There is only one task that must be done for a Marimo: it needs to be squeezed outside of the tank every once in a while. Yes, you should actually squeeze it (as you can’t do with the cheap Java knockoffs).

The Marimo sucks up a lot of filth and debris over time (like a sponge), which is a good thing. But it also absorbs more than it can chew, and the nasty stuff eventually leeches out. So every time you perform a partial water change, just remember to take out the moss ball, squeeze it over a bucket or sink, and toss it right back into the tank. It will float at the surface for a while unless you squeeze it again while underwater. Floating does not hurt the Marimo. In fact, the balls can float up to the surface on their own from internal gasses, as well as sink on their own.

There is technically another task for the moss ball: it should be moved around once in a while to keep its rounded shape, as well as to provide some lighting on every surface to avoid dead patches. But if you are performing routine gravel cleanings and squeezing the moss ball every week or two, then you’re accomplishing this anyway.

So yeah, squeezing the ball once in a great while is the only maintenance required.

6. Easily Adapts to High pH

A lot of aquarium plants don’t do so well in high pH water, but this doesn’t affect moss balls. I have kept moss balls at a pH of 8.4, and they remained healthy.

7. Is Beloved by Shrimp (and Other Creatures)

Because the moss ball collects debris and nutrients over time, small freshwater shrimp enjoy scavenging through the green stuff and munching on any particles to their liking. I have also seen African Dwarf frogs lying on top or snuggling underneath the moss ball. Floating moss balls can even serve as toys for betta fish since they like moving the ball around. All in all, critters can use this ball of algae as a smorgasbord, a comfy hiding place, or a means of entertainment.

8. Is Snail-Proof

Some snails like to munch on live plants, resulting in dead organic matter that needs tossing out. Fortunately, they don’t harm the moss ball. I have had mystery snails, Malaysian Trumpets, Ramshorns, Zebras, and pond snails, and none of them damaged the Marimo. Snails sometimes nibble on the moss ball, eating food off of it like shrimp.

9. Does Not Produce Dead Matter

Lots of plants grow new leaves and lose old ones simultaneously—that's the sign of a healthy plant. But this also means having to remove the decaying parts of the plant from time to time, unless you want your nitrates to go up. No such maintenance for the Marimo! As long as they are healthy, moss balls stay green and intact.

10. Tolerates Salt Well

Aquatic plants don't do so well with salt. Freshwater aquarium salt can be used to treat various injuries and parasitic outbreaks, as well as keep nitrites down during mini-cycles. Salt can actually benefit moss balls, as they are known to live in brackish water.

11. Does Not Bring Hitchhikers With It Into the Tank

When buying live plants from the fish store, you're often buying other creatures with it, from pond snails to tiny creatures not visible to the eye (such as parasites). Luckily moss balls are, for the most part, sold in individual cups. This minimizes the chance of unwanted residences in your fish tank.

12. Doesn't Need to Be Anchored

This is probably one of my favorite benefits of the moss ball, aside from the incredibly low maintenance. A lot of plants need to be anchored, by either burying their roots in gravel or tying them to an object until it attaches itself (which takes patience). It can be a chore to remove anchored plants in order to clean the gravel. I would remove my Java Fern and afterward try to bury it again, which often took a few tries because I have a thin layer of gravel. While struggling to bury all the roots, some small amounts of debris would kick up and that would be really frustrating. It got to the point that I’d just avoid repositioning by vacuuming around it.

The moss ball isn’t meant to be anchored. It doesn’t need to be removed when cleaning gravel. It can merely be pushed aside by the siphon with no damage, and it’s one of the few items I don’t have to remove in order to do a thorough clean.

13. Is Almost Impossible to Kill

The only way to kill a Marimo is if you place it in water full of chlorine (such as untreated tap water), salt water, or a cesspool (where there are no nutrients in the waste).

In other words, as long as you keep up with your maintenance on the tank, providing nutritious food for your animals, the moss ball will thrive. Remember that they prefer dim lighting. White specks on them indicate over-exposure to light. If they have brown patches and/or float up on their own, this means they are not getting enough light (a problem I've never had with them).

Are There Any Disadvantages?

As with anything, there are a few drawbacks to the Marimo.

1. It Doesn't Affect Large Tank Health

While it has the same benefits as plants like absorbing nitrates and providing oxygen, the moss ball does these things on a smaller scale, at least compared to the bigger plants out there. To make a large dent on nitrates, oxygen levels, and the prevention of algae, tanks often have more than just a few plants when we get into double-digit gallons. Often a tank is filled with different species of plants to make a significant impact on tank levels.

To do this with the Marimo, you’d have to fill 1/4 of the tank with moss balls, and that would just look odd. That or have a moss ball the size of a bowling ball.

So if you only want algae or nitrate control (while the moss ball can contribute), you’d have to buy plants in addition. The Marimo just helps with these problems; it doesn’t solve them on its own. So don’t think a single moss ball in a 20-gallon is going to make a significant impact on your tank.

2. Goldfish Eat It

Goldfish are known to eat anything in their paths, so don’t be surprised if your goldfish tears this ball to shreds.

3. It Is Slow-Growing

The Marimo moss ball is the slowest growing plant I’ve ever seen. I’ve heard they can get to be the size of softballs or even bigger, but it takes years (closer to decades) with an enriched environment to get to that size. So if you want a larger ball, you’re in for a wait. If a moss ball is too big, it can be torn apart, resulting in smaller moss balls. You’ll have to regularly move them to make those irregular bits round again.

Of course, this means if you love the size of your moss ball, it will stay that size for a long time.

4. It Does Not Reproduce

While aquatic plants spawn over time, moss balls won’t reproduce in your tank—they just get bigger. So you won’t find little baby moss balls or patches of the algae. This can be good or bad depending on what you want. Only tearing one apart will result in more moss balls, but I'd suggest just buying more. It can be years until a baby moss ball grows to golf ball size.

The Verdict

Overall this is a great little substitute for those of us who have difficulty with aquatic plants. I suggest having more than one in a tank if you want those benefits that plants have. If you want moss balls purely for decoration or as an addition to plant life, they are safe, fool-proof organisms that can only benefit your tank.

Comments

mariekbloch (author) on September 07, 2020:

They would eat off of it. But doubt they would eat the actual moss ball.

mariekbloch (author) on September 07, 2020:

No. Harmless.

Dark Wizard on June 15, 2020:

Will a pleco eat the moss ball

Bob Ross on May 02, 2020:

MOSS BALLS ARE GREAT

Hello on February 27, 2020:

moss balls will reproduce, they will start growing little bumps on them and soon enough those bumps will fall off. I have two and neither of which have died. I also don't know what to do when I sleep because it doesn't get light and I can't rotate it while I sleep. I've been giving it a lot of care but I don't know how to help it while I sleep!

Jeanie on February 21, 2020:

I have one moss ball about the size of a soft ball and it produced a smaller moss ball, about the size of a medium sized marble. All on its own. I have never separated or even tried to separate the big one. Soooo...I’m thinking they must propagate on their own.

Carolyn on December 27, 2019:

I actually did find a very small one in my tank I have 8 larger ones and figured it came off a larger one and rolled itself up in the current from the bubblers

mariekbloch (author) on November 19, 2019:

They'll pick food particles off of it, but they won't eat it. It's a different kind of algae.

Jennifer on November 18, 2019:

I have a Betta, and three ghost shrimp, will the shrimp eat the moss ball?

mariekbloch (author) on November 18, 2019:

Time in the dark is just as natural as time in some light. So yes.

Nikki on November 17, 2019:

I know it needs sunlight, but when its night time is it okay for it to be in the dark or would I still need minimal lighting ?

mariekbloch (author) on September 20, 2019:

Bright green? They can be dark as well. Light will make them look bright.

Cece on September 11, 2019:

Why is my ball not bring green?

mariekbloch (author) on August 09, 2019:

No, they won't hurt bettas.

Linda Licata on August 01, 2019:

Could moss balls harm a betta? I have six small moss balls in a one gallon tank.

mariekbloch (author) on July 28, 2019:

I don't see why not. However, I would suggest putting the betta in a 5 gallon with a soft filter, as a 1 gallon is a bit small for that fish. If you do decide to upgrade its tank, please look up the "nitrogen cycle" for aquariums.

Linda Licata on July 25, 2019:

I have a one gallon tank with a betta. I have six small moss balls. Do you think it will have the benefits of a large moss ball?

M. Wasim Sayed Issa on July 02, 2019:

Thank you, great subject.

Ang on June 19, 2019:

Is it possible to have these without air pump for a 20 gallon? How many would I need?

Fred on June 08, 2019:

I actually have 4 in my 30gal and 2 in my 10gal as I don't seem to do very well with live plants. These things are amazing. Even had a cichlid pushing it all around the tank, almost like playing with it.

Meg Hawkins on March 29, 2019:

Can any other fish besides Betas live in a tank with only the balls?

Anna on February 15, 2019:

marimo balls are actually not moss. they are a type of green algae called Aegagropila linnaei.

So any algae killer will harm this plant.

AwesomeFriend on January 27, 2019:

this was really helpful, I might be getting a new tank and wanting to take it up a notch and make it the ultimate tank

mariekbloch (author) on September 19, 2018:

You're welcome

Mikkimom on September 17, 2018:

Thank you for this article. I didn't really understand the benefits of a Marimo.

A while back my Marimo started turning brown and slimy. When I asked the pet store employee about she said it had probably reached the end of its life and was time to buy a new one (tricky gal). I didn't want to spend more money that day, so I went home. Took the ball out of the (dimly lit) aquarium, and put the ball in a container filled with water and placed it in my sun-room with my other plants. In just a few days it shed the brown slime and became a lovely green again. Now I do this every few months just to give it some natural light and help restore it.

mariekbloch (author) on August 25, 2018:

Youre welcome

Jazz. on August 16, 2018:

Interesting article, thank you!

Deborah Minter from U.S, California on July 25, 2018:

Great article!

mariekbloch (author) on June 26, 2018:

Sure

Suz on June 25, 2018:

I love the whole experience.

My tank is 84°

Can I still have one

mariekbloch (author) on May 22, 2018:

Yes.

Nichol3044 on May 19, 2018:

Can you put these in small ponds

❤️AMY❤️ on May 11, 2018:

Great advice! Helped me a lot now my kid had a fish since 2nd grade now she is in 7th

Lou on April 06, 2018:

I went to a crafts fair where a nice woman was selling them. She gave me the history, and some fun stories. She did however say once they get big enough (these things where huge), they start reproducing. Small little bitty moss balls spawn out of them slowly but surely. Mine is only a few centimeters in diameter right now, but its slowly growing. She showed me the parent moss balls to show how big they can get. Very interesting little green blobs.

Ugh on March 13, 2018:

I've had mine for only a year and it's tripled in size since I got it I never squeezed it or anything except roll it occasionally I got it for my micro shrimp and they didn't seem to like it.

Julius Condemi on February 19, 2018:

Can I use algae killer with marimo moss balls?

Julius Condemi on February 19, 2018:

Can I use algae ki

Lynn Dostal on February 10, 2018:

can I use in tilapia tank or will the fish consume it?

Moss owner on February 03, 2018:

i have 4 marimos in my tank. 3 normal ones and 1 floating one. they are amazing. the shrimp in the tank nibble 0n them and the shrimp hang upside down while nibbling on the floating ball. They are so cute!

Morgan on January 29, 2018:

I got a moss ball for my Betta Fish today, so I found this article and it was really interesting. Million seems to love it!!! He was a bit skeptical at first, but he seems to have gotten used to it already!!! I didn’t notice all the positive effects it has, and his tank has never looked better!!!

alan on January 11, 2018:

Verry helpful keep up the good work

Lol on December 26, 2017:

Probably not

Tweetdy Bui on September 07, 2017:

Very good info. Dose Beta fish like to eat this moss? Do Pet Smart stores have this moss?

Thank you

Barb78 on August 31, 2017:

I just got some of the Marimo balls at a reasonable price on the Amazon. I'm just setting up a fresh water tank for present for my daughter. I just wondering at what point should I add the balls in? I have just literally got tank set up and put in water and the water conditioner so far not added biological booted as yet.

If it is not soon do they survive out of water for long?

As they came today through the post in a sealed package with a minimal moister.

Can I put them in a dish with a bit of water? Or does it need to be full submerged while waiting for tank to be ready? And can I use just tap water and wait 24h before putting them in that water or should I just use rain water? At the minute they are still in plastic bag so not to dry out. Ps found you page very interesting informative and well written.

Sharon on August 10, 2017:

Just received two today for my 72nd birthday. They rode the 100 miles home with me and I already consider them pets. Your article is excellent and just what I needed. I've always loved Bettas but feel somewhat disturbed that they must live alone, so never purchased one. Maybe now!

Timophy on July 30, 2017:

Wow I can't wai to o get mine!!

Aquatic Guru on June 14, 2017:

Question.... a lot of keepers of the Moss Ball insist on squeezing them periodically . I find this unnecessary. No one squeezes them in the wild and it looks like squeezing them would be robbing them of their nutrition . I never squeeze my Moss Balls and they are growing a lot faster than the estimated annual growth . I breed Fish and my tanks are very healthy . So is squeezing them really the thing to do? Just wondering.

hacker on April 17, 2017:

woah, it's indestructible? ok, i'll keep mine forever.

va_China on April 04, 2017:

What about a regular lobster?

Raldo on February 09, 2017:

Could my blue australian lobster eat this? If so would he die of over feeding by eating the whole thing because he is known to eat everything in his path.

Don Pratt from United States on January 31, 2017:

Awesome information ! Thanks for reminding me about these amazing little green balls ! I need to get a few .

Sofie on January 08, 2017:

Wow. Indestructible. Ruler of worlds. I will keep my moss ball forever.

Carol B on December 27, 2016:

This is Great info. I bought a Marino ball when I bought a Betta fish not really knowing anything about it. This article showed me that I could really use it to regulate the water & for the betta to play with. Thanks for this article!

Robert on December 21, 2016:

I've had mine in my 30 gal tank for about 3 years now. Started out the size of a large marble and is now the size of a hard baseball. Paid about $3 for it.

Question: Can it be cut in half and used in another tank?

Hugh Guestit on July 06, 2016:

I once had Marimo ball in a 55 gal tank that I ripped apart...It grew astronomically fast. I accidentally used the net I use with my 55, on my 40, and a piece of Marimo must have transferred...but it has grown at a MUCH faster rate than what anyone else says online...I actually am looking for a way to destroy it because it is overtaking the 40 gal, and I have plants in that tank. The tank gets dry ferts too, so that doesn't help at all...The only viable option has been to manually remove bits of it, and it is indeed, positively, Marimo "moss"

Alyssa on April 13, 2016:

I bought my Marimo for $8

Ned Pepper on March 27, 2016:

This article is more fiction than fact. Marimo are stealth predators eating any fish that gets too close ... they stick to the spiny tendrils and get sucked in. If you notice a fish disappear, and a skeleton lying by your Marimo, just know that it was not a friendly collision.

Kellie Simms on March 13, 2016:

You're Moss Ball information is and has been exactly what I was looking for, thanks so much for the information and may be of our Green Moss Balls grow!

Doreen on March 05, 2016:

Great article! If it's suppose to control algae, would it be smart to not put one in with algae eaters?

Linda Robinson on March 02, 2016:

Hello Marie, excellent hub. It is fascinating and extremely informative, everyone and anyone interested in tanks, and fish should definitely read your hub, so much terrific information. So nice meeting you. Linda

BirdieGal on February 24, 2016:

I have a 2 gallon tank with a filter for my betta fish. I had two small plants in it that I struggled to keep going and some amount of algae on the rocks on the bottom. I was finally able to find real Marimo moss balls at my local Petsmart so I grabbed one when I went looking for a new plant for Phinnigan. Bought one plant and the ball. Did a complete cleaning of tank, rocks, etc.. The tank has never looked better. It has been in there for 2 weeks now and nothing...NOTHING is starting to grow on the bottom and the water is crystal clear. I wondered what the exact benefits of the ball were so I searched and found your article. Great job, very informative. Phin loves his ball and will even rest on it. I don't suppose another one would hurt so I will pick up one more. Love the way they look as well!

Asher Socrates from Los Angeles, CA on February 21, 2016:

This moss ball is such a great addition to an aquarium. It adds to the aesthetics to the natural habitat but very beneficial as well. Great write up and very informative. I love this hobby and have had both fresh and saltwater aquariums with live plants and fish. It's very therapeutic to the soul and mind. Cheers!

Jeff Boettner from Tampa, FL on February 16, 2016:

Awesomeness! can I put one of these in my Koi pond? The PH is high, water is filtered etc., but is of course outdoors (though within a semi-closed patio-deck). I have a small pond for the baby Koi, wondering If I could put one of these in that for starters?

James Bowden from Long Island, New York on February 16, 2016:

Very interesting and useful article about the Marimo moss ball. I had something similar in my freshwater aquarium. However it was sold at Petco where I picked it up about a week ago.

It was suspended on a nylon string attached to a rock to weigh it down. So this right away tells me it was basically some sort of floating plant used mainly as a tank ornament.

However when I stopped into another Petco today, I did come across the Marimo moss ball. They were selling it under the name fluval moss ball though. And so I bought this golf ball sized moss ball - possibly an imitation for $5.99 And not the $18-23 you mentioned near the beginning of your article.

Wish I could attach a pic to my comment here. But do not see a feasible way to do so. So anyway I placed the fluval moss ball in my tank this evening. Had to squeeze it a bit to get it to finally sink to the gravel bed on the bottom.

So I will see if this is similar to the Marimo Moss ball, or a imitation in which fluval used their name on. Otherwise still interesting stuff and congrats on your article making Hub of The Day. Now that's something really worth talking about!

Jlbowden

ignugent17 on February 16, 2016:

Congratulations hub of the day!

RTalloni on February 16, 2016:

Such an interesting tank plant to learn about. Congrats on your Hub of the Day award!